How to assign an ad to two different groups, each belonging to different channels

I have created 20 different channels. Each ad belongs to a channel.
And created 2 groups: Group1 and Group2.
This is what I need to do: Group1 shows ads for the channel, Group2 shows any ad.
I created a channel with no restriction ("All"), and only allowed Group2. Channels 1 to 20 only allow Group1.
When I create an ad I get

* The Channel1 channel does not allow advertisements from the Group2 group.
* The All channel does not allow advertisements from the Group1 group.

So, is the only solution to duplicate the ad?

Note: my question http://drupal.org/node/844016 which is unanswered has a better way to do it, if only I could do it.